Make a pure mojo::View version of the aura::Window FocusController.

mojo/services/window_manager/focus_controller.h

Index: mojo/services/window_manager/focus_controller.h
diff --git a/mojo/services/window_manager/focus_controller.h b/mojo/services/window_manager/focus_controller.h
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+++ b/mojo/services/window_manager/focus_controller.h
@@ -0,0 +1,99 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_SERIVCES_WINDOW_MANAGER_FOCUS_CONTROLLER_H_
+#define MOJO_SERIVCES_WINDOW_MANAGER_FOCUS_CONTROLLER_H_
+
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
+#include "base/scoped_observer.h"
+#include "mojo/services/public/cpp/view_manager/view_observer.h"
+#include "ui/events/event_handler.h"
+
+namespace mojo {
+
+class FocusControllerObserver;
+class FocusRules;
+
+// TODO: Maybe write a better comments.

[sky, 2014/11/10 20:45:30]

At least write a description for the class.

+
+class FocusController : public ui::EventHandler,
+                        public ViewObserver {
+ public:
+  // |rules| cannot be NULL.
+  explicit FocusController(FocusRules* rules);
+  virtual ~FocusController();
+
+  void AddObserver(FocusControllerObserver* observer);
+  void RemoveObserver(FocusControllerObserver* observer);
+
+  void ActivateView(View* view);
+  void DeactivateView(View* view);
+  View* GetActiveView();
+  View* GetActivatableView(View* view);
+  View* GetToplevelView(View* view);
+  bool CanActivateView(View* view) const;
+
+  void FocusView(View* view);
+
+  void ResetFocusWithinActiveView(View* view);
+  View* GetFocusedView();
+
+  // Overridden from ui::EventHandler:
+  void OnKeyEvent(ui::KeyEvent* event) override;
+  void OnMouseEvent(ui::MouseEvent* event) override;
+  void OnScrollEvent(ui::ScrollEvent* event) override;
+  void OnTouchEvent(ui::TouchEvent* event) override;
+  void OnGestureEvent(ui::GestureEvent* event) override;
+
+  // Overridden from ViewObserver:
+  void OnTreeChanging(const TreeChangeParams& params) override;
+  void OnTreeChanged(const TreeChangeParams& params) override;
+  void OnViewVisibilityChanged(View* view) override;
+  void OnViewDestroying(View* view) override;
+
+ private:
+

[sky, 2014/11/10 20:45:30]

nit: generally no newline here.

+  // Internal implementation that sets the focused view, fires events etc.
+  // This function must be called with a valid focusable view.
+  void SetFocusedView(View* view);
+
+  // Internal implementation that sets the active window, fires events etc.
+  // This function must be called with a valid |activatable_window|.
+  // |requested window| refers to the window that was passed in to an external
+  // request (e.g. FocusWindow or ActivateWindow). It may be NULL, e.g. if
+  // SetActiveWindow was not called by an external request. |activatable_window|
+  // refers to the actual window to be activated, which may be different.
+  void SetActiveView(View* requested_view,
+                     View* activatable_view);
+
+  // Called when a window's disposition changed such that it and its hierarchy
+  // are no longer focusable/activatable. |next| is a valid window that is used
+  // as a starting point for finding a window to focus next based on rules.
+  void ViewLostFocusFromDispositionChange(View* view, View* next);
+
+  // Called when an attempt is made to focus or activate a window via an input
+  // event targeted at that window. Rules determine the best focusable window
+  // for the input window.
+  void ViewFocusedFromInputEvent(View* view);
+
+  View* active_view_;
+  View* focused_view_;
+
+  bool updating_focus_;
+  bool updating_activation_;
+
+  scoped_ptr<FocusRules> rules_;
+
+  ObserverList<FocusControllerObserver> focus_controller_observers_;
+
+  ScopedObserver<View, ViewObserver> observer_manager_;
+
+  DISALLOW_COPY_AND_ASSIGN(FocusController);
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_SERIVCES_WINDOW_MANAGER_FOCUS_CONTROLLER_H_